Sealing structure of spindle bolt, and gas turbine

ABSTRACT

A first stage rotor disk ( 50   a ) and a connecting member ( 30 ) on the compressor side are fixed by a spindle bolt ( 20 ). The spindle bolt ( 20 ) is covered with a tubular member ( 100 ), between the first stage rotor disk ( 50   a ) and the connecting member ( 30 ) on the compressor side.

TECHNICAL FIELD

[0001] The present invention relates to a gas turbine that uses steam asa cooling medium for hot members. More particularly, the presentinvention relates to a gas turbine in which steam leakage is decreasedto increase the use efficiency of the steam, to thereby enable efficientoperation, and a sealing structure for a spindle bolt connecting rotordisks.

BACKGROUND ART

[0002] A technique for cooling hot members, such as a rotor blade, arotor disk, or a stationary blade in a gas turbine, by using steaminstead of air as a cooling medium, is now being used, in order toincrease the thermal efficiency in the gas turbine. This is due to thefollowing reasons. The specific heat at constant pressure of dry steamis cp=1.86 kJ/kgK under a normal condition, which is a value almosttwice as large as the specific heat at constant pressure of air, cp=1.00kJ/kgK. Therefore, steam has a large heat capacity and a highendothermic effect, as compared with air of the same mass. Further, whenwet steam is used as the cooling medium, the endothermic effect can befurther increased, since the latent heat of vaporization for the wetamount can be also used for cooling. Hence, the cooling efficiency canbe increased than when using air, and the turbine inlet temperature ofthe combustion gas can be increased, thereby enabling an improvement inthe thermal efficiency.

[0003] In the conventional air cooling, air from a compressor is used asa cooling medium for rotor and stationary blades of the turbine.However, when this compressed air is used for cooling, the work that canbe taken out from the turbine decreases. If steam is used instead ofair, the cooling air for the rotor and stationary blades can be saved,and hence the work that can be recovered by the turbine increases bythis amount, thereby the work that can be taken out from the turbine canbe increased.

[0004]FIG. 15 shows a rotor disk in a gas turbine conventionally used. Aplurality of first stage rotor disks 500 a to 500 d are fastened by aspindle bolt 520 and nuts 510, to thereby constitute a rotor 600 of agas turbine. Spaces between the rotor disks 550, 551 and 552 become apath for flowing steam supplied to the rotor blade (not shown), andcooling steam is supplied from a hollow turbine main spindle 560 side.This steam flows through the path formed by the spaces 550 and 551, andis supplied to the rotor blade from the space between the first stagerotor disk 500 a and the second stage rotor disk 500 b.

[0005] However, since the steam pressure on the rotor disk side ishigher than the air pressure on a compressor side, the steam on therotor disk 500 a side leaks towards the compressor side, through a bolthole provided in the first stage rotor disk 500 a. The amount of leakageis not large as seen from the whole feed rate of the steam, butrecently, it is tried to suppress the steam leakage, even in a smallamount, and to use the cooling steam as effectively as possible.Therefore, it is necessary to reduce the steam leakage in this part asmuch as possible.

[0006] It is therefore an object of the present invention to provide agas turbine that can reduce the leakage of steam to be used for coolingthe rotor blade and the like and increase the use efficiency of thesteam, thereby enabling efficient operation, and a sealing structure ofthe spindle bolt for connecting the rotor disks.

DISCLOSURE OF THE INVENTION

[0007] A sealing structure of a spindle bolt according to the presentinvention is such that rotor disks and a connecting member on acompressor side are fixed by a spindle bolt, and between the first stagerotor disk and the connecting member on the compressor side, of aturbine rotor in a gas turbine having a steam path therein, thecircumference of the spindle bolt is covered with a tubular member inwhich a section thereof vertical to the axial direction includes asection of a bolt hole for passing the spindle bolt therethrough, andthe ends of the tubular member are made to abut on the first stage rotordisk and the connecting member on the compressor side, respectively.

[0008] In this sealing structure of this spindle bolt, the tubularmember covers the circumference of the spindle bolt to thereby seal thesteam leaking through the bolt hole provided in the first stage rotordisk by this tubular member. Therefore, since the steam leakage can bereduced to effectively use the steam, the operation cost can be reduced.The cooling steam is generated by the exhaust gas of the gas turbine,and after cooling the rotor blade, drives an intermediate pressureturbine and the like. Since the consumption of steam in this part can besuppressed, the thermal efficiency is improved as a steam and gasturbine combined cycle power plant. The tubular member in this inventionincludes not only the one in which the cross section vertical to theaxial direction is circular, but also tubular members in which the crosssection is polygonal such as triangular and quadrangular. The tubularmember may be formed integrally with the rotor disk and the connectingmember on the compressor side.

[0009] A sealing structure of the spindle bolt according to the nextinvention is such that rotor disks and a connecting member on acompressor side are fixed by a spindle bolt, and of a turbine rotor in agas turbine having a steam path therein, a first annular member and asecond annular member arranged inside the first annular member arearranged so that the ends thereof abut on the first stage rotor disksand the connecting member on the compressor side, and the spindle boltis passed between the first annular member and the second annularmember.

[0010] In this sealing structure of the spindle bolt, two annularmembers having a different outer dimension are arranged between thefirst stage rotor disk and the connecting member on the compressor side,and the spindle bolt is passed between these two annular members, toprevent the steam leaking from a bolt hole, through which the spindlebolt passes. Since steam leakage is reduced, and steam can be usedeffectively, the operation cost can be reduced. Since the consumption ofsteam in this part can be reduced, the thermal efficiency is improved asa steam and gas turbine combined cycle power plant. The annular memberin this invention includes not only the one in which the cross sectionvertical to the axial direction is circular, but also annular members inwhich the cross section is polygonal such as triangular andquadrangular, and stelliform. The annular member may be formedintegrally with the rotor disk and the connecting member on thecompressor side.

[0011] A sealing structure of the spindle bolt according to the nextinvention is such that, in the sealing structure of the spindle bolt, asealant is provided at least on one side of between the end of thetubular member or the annular member and the first stage rotor disk, andbetween the end of the tubular member or the annular member and theconnecting member on the compressor side. In the sealing structure ofthe spindle bolt, a metal or ceramics sealant is provided at the end ofthe tubular member or the annular member, to increase the steam sealingperformance. Therefore, since the steam leakage can be further reduced,the steam can be used more effectively, and the thermal efficiency asthe steam and gas turbine combined cycle power plant is also improved.

[0012] A sealing structure of the spindle bolt according to the nextinvention is such that, in the sealing structure of the spindle bolt, aprotrusion or a step that hinders the tubular member or the annularmember from moving radially outwards of the rotor disk, is provided atleast on one side of the first stage rotor disk and the connectingmember on the compressor side.

[0013] In the sealing structure of the spindle bolt, a step or the likeis provided in the first stage rotor disk or the like, so as to preventthe tubular member or the annular member from moving radially outwardsof the rotor disk due to a centrifugal force. Since the rotor disk ofthe gas turbine rotates at a high speed, the structural members in therotating system are subjected to a large centrifugal force. When thetubular member or the annular member is eccentric due to the centrifugalforce, the rotation balance is lost and spindle vibration increases,thereby a trip of the gas turbine may occur. In this sealing structure,since the movement of the tubular member or the like is hindered bymaking the step or the like abut on the tubular member, a deviation ofthe tubular member or the like can be suppressed. As a result, since thegas turbine can be operated without losing the rotation balance, andhence a trip of the gas turbine can be suppressed.

[0014] A gas turbine according to the next invention is a gas turbinethat has a plurality of rotor disks having a rotor blade in theperiphery thereof, which cools the rotor blade or the rotor disk, andother hot members by steam. The gas turbine comprises a compressor thatcompresses air to produce combustion air, a combustor that supplies fuelto the combustion air produced by the compressor to generate combustiongas, and a turbine rotor having a feed path or a recovery path for thesteam therein, in which rotor disks and a connecting member located onthe compressor side are fixed by a spindle bolt, wherein between thefirst stage rotor disk and the connecting member, the circumference ofthe spindle bolt is covered with a tubular member in which a sectionthereof vertical to the axial direction includes a section of a bolthole for passing the spindle bolt therethrough, and the opposite ends ofthe tubular member are made to abut on the first stage rotor disk andthe connecting member on the compressor side, respectively.

[0015] This gas turbine uses a turbine rotor having a sealing structure,in which a tubular member covers the circumference of the spindle bolt,and steam leaking from a bolt hole provided in the first stage rotordisk is sealed by the tubular member. Therefore, steam leakage at thespindle bolt portion can be reduced. As a result, in this gas turbine,wasteful use of the cooling steam can be suppressed. Further, in a steamand gas turbine combined cycle power plant using this gas turbine,thermal efficiency can be increased.

[0016] A gas turbine according to the next invention is a gas turbinethat has a plurality of rotor disks having a rotor blade in theperiphery thereof, which cools the rotor blade or the rotor disk, andother hot members by steam. The gas turbine comprises a compressor thatcompresses air to produce combustion air, a combustor that supplies fuelto the combustion air produced by the compressor to generate combustiongas, and a turbine rotor having a feed path or a recovery path for thesteam therein, in which rotor disks and a connecting member located onthe compressor side are fixed by a spindle bolt, wherein a first annularmember and a second annular member arranged inside the first annularmember are arranged so that the ends thereof abut on the first stagerotor disks and the connecting member, and the spindle bolt is passedbetween the first annular member and the second annular member.

[0017] In this gas turbine, two annular members having a different outerdimension are arranged between the first stage rotor disk and theconnecting member on the compressor side. The gas turbine uses a turbinerotor having a sealing structure, in which a spindle bolt is passedbetween these two annular members so as to prevent the steam leakingfrom a bolt hole, through which the spindle bolt passes. Therefore,steam leakage at the spindle bolt portion can be reduced. As a result,in this gas turbine, wasteful use of the cooling steam can besuppressed. Further, in a steam and gas turbine combined cycle powerplant using this gas turbine, thermal efficiency can be increased.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 shows a gas turbine according to a first embodiment of thepresent invention;

[0019]FIG. 2 is a partial enlarged view that shows a sealing structureof a spindle bolt according to this gas turbine;

[0020]FIG. 3 shows a section of a tubular member and a section of a bolthole; FIG. 4 is a local sectional view that shows a sealing structure ofa spindle bolt according to a first modified example in the firstembodiment;

[0021]FIG. 5 is a local sectional view that shows a sealing structure ofa spindle bolt according to a second modified example in the firstembodiment;

[0022]FIG. 6 is a local sectional view that shows a sealing structure ofa spindle bolt according to a third modified example in the firstembodiment;

[0023]FIG. 7 is a local sectional view that shows a sealing structure ofa spindle bolt according to a second embodiment;

[0024]FIG. 8 shows an example of an annular member;

[0025]FIG. 9 is a local sectional view that shows a first modifiedexample in the second embodiment;

[0026]FIG. 10 is a local sectional view that shows a sealing structureof a spindle bolt according to a second modified example of the secondembodiment;

[0027]FIG. 11 is a local sectional view that shows a sealing structureof a spindle bolt according to a third embodiment of the presentinvention;

[0028]FIG. 12 is a local sectional view that shows a sealing structureof a spindle bolt according to a modified example of the thirdembodiment;

[0029]FIG. 13 is a local sectional view that shows a sealing structureof a spindle bolt according to a fourth embodiment of the presentinvention;

[0030]FIG. 14 is a schematic diagram that shows a steam and gas turbinecombined cycle power plant adopting steam cooling for cooling hotmembers; and

[0031]FIG. 15 shows a rotor disk of a gas turbine conventionally used.

BEST MODE-FOR CARRYING OUT THE INVENTION

[0032] The present invention will be explained in detail, with referenceto the drawings, but the present invention is not limited by theembodiments. The components in the embodiments include ones that can beassumed easily by those skilled in the art.

[0033] First Embodiment

[0034]FIG. 1 shows a gas turbine according to a first embodiment of thepresent invention. A gas turbine 10 is for cooling hot members of thegas turbine, such as a rotor blade, a rotor disk, or a stationary bladeby steam. Air taken in from an air intake 11 is compressed by acompressor 12, to become high temperature and high pressure compressedair, and is fed to a combustor 13. The combustor 13 supplies gas fuelsuch as natural gas or the like, or liquid fuel such as gas oil, lightfuel oil or the like to the compressed air, to burn the fuel, to therebygenerate high temperature and high pressure combustion gas. This hightemperature and high pressure combustion gas is guided to a combustortail pipe 14, and injected to a turbine 15.

[0035] The stationary blade and the rotor blade of the turbine 15 arecooled by steam, and this is supplied through a steam feed path (notshown) provided in a turbine main spindle 16. The steam supplied fromthe steam feed path changes the direction by 90 degrees in front of therotor disk 50, is guided to a plurality of outer steam passes 60provided in the circumferential direction of the rotor disk 50, and isthen supplied to the rotor blade. The rotor disks 50 are fixed by aplurality of spindle bolts (not shown) axially penetrating the rotordisks 50, to thereby constitute a rotor of multiple stages.

[0036]FIG. 2 is a partially enlarged view that shows a sealing structureof a spindle bolt according to this gas turbine. This structure has afeature in that the spindle bolt connecting the rotor disks is coveredby a tubular member, so as to prevent the leakage of steam from the highpressure side, from a gap between the spindle bolt and a bolt hole. Asshown in FIG. 2, a first stage rotor disk 50 a and a connecting member30 on the compressor side are fastened by a spindle bolt 20 penetratingboth the members. Between the first stage rotor disk 50 a and theconnecting member 30 on the compressor side, a tubular member 100 coversthe spindle bolt 20.

[0037] The length L1 of this tubular member 100 is set slightly largerthan a gap L between the first stage rotor disk 50 a and the connectingmember 30 on the compressor side (see FIG. 2(b)). When the first stagerotor disk 50 a and the connecting member 30 on the compressor side arefastened by the spindle bolt 20, the tubular member shrinks, therebybecomes the same length as the gap L. The tubular member 100 shrinks byL1−L, and the tubular member is pressed against the first stage rotordisk 50 a and the connecting member 30 on the compressor side by theresilience of this shrunken portion. As a result, the steam sealingperformance increases by this portion.

[0038] Ends 100 a and 100 b of the tubular member 100 abut on the firststage rotor disk 50 a and the connecting member 30 on the compressorside. The abutted portions of the tubular member 100 and the first stagerotor disk 50 a and the like are machined smoothly, so that the steampassing through the space between the tubular member 100 and the firststage rotor disk 50 a and the like is reduced as much as possible. Thesteam leaking from a bolt hole 25 on the first stage rotor disk 50 aside and the spindle bolt 20 is confined within the tubular member 100,and hence steam leakage can be suppressed. According to the sealingstructure of the spindle bolt, since the amount of steam leaking fromthe first stage rotor disk 50 a to the compressor side can besuppressed, the use efficiency of the steam can be increased.

[0039] The relation between the section of the tubular member 100 andthe section of the bolt hole 25 is explained in FIG. 3. FIGS. 3(a), (c)and (e) respectively show examples in which the external shape of thebolt hole 25 is included in the inner section of the tubular member 100or the like. FIGS. 3(b) and (d) show examples in which the externalshape of the bolt hole 25 is included between the inner wall and theexternal wall of the tubular member 100 or the like. In either case, itcorresponds to the relation of “a section of a tubular member verticalto the axial direction includes a section of a bolt hole” in the presentinvention. As is clearly seen from these figures, the cross section ofthe tubular member 100 is not limited to a circular shape, and as shownin FIGS. 3(c) and (e), it includes polygonal shapes such as quadrangleand hexagon. Though not shown in these figures, an ellipse and one inwhich either the external shape or the inner diameter is circular andthe other is polygonal are also included.

FIRST MODIFIED EXAMPLE

[0040]FIG. 4 is a local sectional view that shows a sealing structure ofa spindle bolt according to a first modified example in the firstembodiment. The sealing structure of the spindle bolt has a feature inthat a sealant is provided between the tubular member and the connectingmember on the compressor side. At the end of the tubular member 100 usedin this sealing structure, a step 130 is provided, and a sealing member120 is put in this step 130. Since the temperature of the first stagerotor disk 50 a and the like rises during the operation of the gasturbine, heat resistance is required for the sealing member 120. Thissealing member 120 should also have resilience, so as to absorbelongation of the tubular member 100, a curvic coupling 125 and thelike. A metal seal or a ceramics seal may be used for this sealingmember 120, in order to satisfy such requirement.

[0041] In this example, the sealing member 120 is provided in thetubular member 100, but the sealing member 120 may be provided in theconnecting member 30 on the compressor side or the first stage rotordisk 50 a. In that case, if a spot facing is provided in the bolt hole25, through which the spindle bolt passes, in the connecting member 30on the compressor side or the like, and the sealing member 120 is fittedtherein, stable sealing performance can be demonstrated, whilesuppressing a deviation of the sealing member. Therefore, it ispreferable. As shown in FIG. 4(a), this sealing member 120 may beprovided only on the connecting member 30 on the compressor side, but inorder to exhibit higher sealing performance, as shown in FIG. 4(b), itis desired to provide the sealing member 120 at the opposite ends of thetubular member 101 a.

[0042] When the first stage rotor disk 50 a and the connecting member 30on the compressor side are combined, after the spindle bolt 20 isinserted in the tubular member 100, nuts 24 (see FIG. 2) are fastened toassemble. When the nuts 24 are fastened, the sealing member 120 providedin the tubular member 100 shrinks axially due to the clamping force ofthe nuts 24, and hence the steam leaking from the bolt hole 25 in thefirst stage rotor disk 50 a can be sealed.

SECOND MODIFIED EXAMPLE

[0043]FIG. 5 is a local sectional view that shows a sealing structure ofa spindle bolt according to a second modified example in the firstembodiment. The sealing structure of the spindle bolt has a feature inthat machining such as spot facing is provided to the connecting memberon the compressor side or the first stage rotor disk, to form a step,and the end of the tubular member is fitted therein to thereby preventthe tubular member from moving radially outwards of the rotor disk. Thebolt hole 25 for the spindle bolt 20 is provided in a connecting member31 on the compressor side used for this sealing structure. The outlet ofthe bolt hole 25 is subjected to spot facing machining, to form a step31 a. As shown in FIG. 5(a), the end of the tubular member 102 is fittedin this step 31 a. For this tubular member 102, a tubular member havinga sealing member 120 (see FIG. 4) explained in the first modifiedexample may be used. By using this, the sealing performance can befurther increased, and hence the steam leakage can be further reduced.

[0044] When the connecting member 31 on the compressor side rotates bythe operation of the gas turbine, the tubular member 102 also rotates,and is subjected to a centrifugal force attributable to the rotation.Since the connecting member 31 on the compressor side and the firststage rotor disk 50 a rotate at a speed as high as 3000 or 3600 rpm, thecentrifugal force acting on the tubular member 102 becomes large. As aresult, the tubular member 102 may move radially outward of theconnecting member 31 on the compressor side, to thereby decrease thesteam sealing performance. In the sealing structure of the spindle boltaccording to this modified example, since the movement of the tubularmember 102 can be hindered by the step 31 a provided in the connectingmember 31 on the compressor side, the steam sealing performance can beensured even during the operation of the gas turbine. As a result,stable steam sealing performance can be exhibited, regardless of theoperation condition of the gas turbine, to thereby minimize the steamleakage.

[0045] When the tubular member 102 moves in the radial direction of thefirst stage rotor disk 50 a, the balance of the rotating system is lost,and the spindle vibration may exceed a tolerance. Thereby, a trip(suspension) of the gas turbine may occur. However, by this modifiedexample, such radial movement of the tubular member 102 can be hindered,and hence the balance of the rotating system is hardly affected.Therefore, even if the tubular member 102 is provided, the spindlevibration can be suppressed within the tolerance, and hence a trip ofthe gas turbine can be avoided.

[0046] In the example, the step 31 a is provided only in the connectingmember 31 on the compressor side, but as shown in FIG. 5(b), spot facingmachining may be also applied to the bolt hole 25 in the first stagerotor disk 51 a, to provide a step 51 ax. By providing the step 51 ax,the movement of this member can be received by the opposite ends of thetubular member 102, and hence the movement of the tubular member 102 canbe inhibited more stably. FIG. 5(c) shows another method for inhibitingthe movement of the tubular member 102. As shown in this figure, aprotrusion 80 is provided at the outlet of the bolt hole 25, to preventthe movement of the tubular member 102 by this protrusion 80.

THIRD MODIFIED EXAMPLE

[0047]FIG. 6 is a local sectional view that shows a sealing structure ofa spindle bolt according to a third modified example in the firstembodiment. The sealing structure of the spindle bolt has a feature inthat a tubular member covering the spindle bolt is integrally formed atleast on one side of the connecting member on the compressor side andthe first stage rotor disk. FIG. 6(a) shows an example in which atubular member 103 is formed in a first stage rotor disk 52 a. FIG. 6(b)shows an example in which tubular members 104 and 105 are respectivelyformed in a first stage rotor disk 53 a and a connecting member 33 onthe compressor side, and the ends of the tubular members 104 and 105 aremade to abut on each other, to thereby seal the steam leakage from thebolt hole 25.

[0048] In this sealing structure according to this modified example, inaddition to the action and effect exhibited by the sealing structureaccording to the first embodiment, the first stage rotor disk 52 a andthe tubular member 103 and the like are integrally formed, and hence adeviation of the tubular member 103 does not occur. Therefore, it is notnecessary to provide deviation preventing means for the tubular member103, and hence the structure becomes simple, and the reliability can beincreased. Further, since it has an integral structure, the strength canbe also increased, to thereby improve the durability. The sealing membermay be provided on the sealing plane where the tubular member 103 or thelike comes in contact with the connecting member 32 on the compressorside or the like. Such a structure helps to increase the steam sealingperformance, reduce the steam leakage, and hence improve the thermalefficiency of the gas turbine. As shown in FIG. 6(c), the configurationmay be such that an external thread is provided in a tubular body 107,an internal thread engaging therewith is provided in a connecting member34 on the compressor side, and the tubular body 107 is screwed thereinto form a tubular member. By having such a configuration, machiningbecomes easy, and even when the tubular body 107 is broken, replacementbecomes easy.

[0049] Second Embodiment

[0050]FIG. 7 is a local sectional view that shows a sealing structure ofa spindle bolt according to a second embodiment. In this sealingstructure, two annular members having a different diameter are providedbetween the connecting member on the compressor side and the first stagerotor disk, and a spindle bolt is passed between these two annularmembers, to thereby fix the connecting member on the compressor side andthe first stage rotor disk. It has a feature in that the steam leakingfrom the bolt hole provided in the first stage rotor disk is sealed bythe two annular members.

[0051] Two annular members 108 and 109 having a different diameter areprovided between a connecting member 35 on the compressor side and afirst stage rotor disk 54 a. Spindle bolts 20 pass between the annularmember 109 having a small diameter and the annular member 108 having alarge diameter, to fasten the connecting member 35 on the compressorside and the first stage rotor disk 54 a. As shown in FIG. 7(c), thelength L2 of the annular members 108 and 109 is slightly larger than agap L between the connecting member 35 on the compressor side and thefirst stage rotor disk 54 a, and the annular members shrink by ashrinkage allowance Δ=L2−L, by fastening the spindle bolts 20. Since theworking face can be compressed by this shrinkage allowance Δ, stablesealing performance can be exhibited, regardless of the operationcondition of the gas turbine.

[0052] As explained in the first embodiment, a sealing member (notshown) may be provided at the ends of the annular members 108 and 109.Since the steam sealing performance can be increased by this sealingmember, the waste of steam can be reduced than when the sealing memberis not provided, and hence it is preferable. As the material of thissealing member, one explained in the first embodiment can be applied.

[0053] The steam on the first stage rotor disk 54 a tends to leaktowards the compressor side, from the gap between the bolt hole 25provided in the rotor disk and the spindle bolt 20. However, the steamstays in a space A (a portion surrounded by a dotted line in FIG. 7)formed between the annular members 108 and 109 having a differentdiameter, and does not leak outside of this space A, and hence the steamleaking from the first stage rotor disk 54 a can be sealed. As a result,the waste of steam can be further reduced, and the thermal efficiency ofthe gas turbine can be further increased.

[0054]FIG. 8 shows an example of an annular member. FIG. 8(a) showsoctagonal annular members 108 a and 109 a, and FIG. 8(b) shows hexagonalannular members 108 b and 109 b. The annular members include not onlythe annular member in which a section thereof vertical to the axialdirection is circular, but also annular members in which the sectionthereof vertical to the axial direction is polygonal such as octagonalor hexagonal. As shown in FIG. 8(c), an annular member 108 c in whichthe section thereof vertical to the axial direction is substantiallystelliform is also included. As a combination of the annular members,the same type of shapes may be combined, such as a combination of around shape and a round shape, or different shapes may be combined, suchas a combination of a round shape and a polygon.

FIRST MODIFIED EXAMPLE

[0055]FIG. 9 is a sectional view that shows a first modified example inthe second embodiment. As shown in FIG. 9(a), a step 55 ax or the likemay be provided in a first stage rotor disk 55 a or the like, so thatthe step 55 ax inhibits the annular members 108 and 109 from movingradially. As shown in FIG. 9(b), a protrusion 81 may be provided insteadof the step 55 ax, to inhibit the radial movement of the annular members108 and 109. In this manner, preventing the radial movement of theannular members 108 and the like, demonstrates stable sealingperformance. Further, this suppresses the change in rotation balance dueto the movement of the annular member 108 and the like, and thereforeavoids a trip of the gas turbine due to an increase of the spindlevibration. As a result, the gas turbine can be stably operated, whilesuppressing the steam leakage as much as possible.

[0056] If the section of the annular member is made circular, thecentrifugal force acts on the annular member substantially uniformly,and hence the movement due to the centrifugal force decreases than inthe case of the tubular member explained in the first embodiment.Therefore, the sealing performance can be ensured, and the spindlevibration can be kept within a tolerance limit, without providing shiftpreventing means such as the step 55 ax, depending on the design.

SECOND MODIFIED EXAMPLE

[0057]FIG. 10 is a local sectional view that shows a sealing structureof a spindle bolt according to a modified example of the secondembodiment. The sealing structure of the spindle bolt according to thismodified example has a feature in that the annular member is integrallyformed at least on one side of the connecting member on the compressorside and the first stage rotor disk. FIG. 10(a) shows an example inwhich annular members 110 a and 110 b having a different diameter areformed in a first stage rotor disk 55 a, and FIG. 10(a) shows an examplein which an annular member 111 a, 111 b is respectively formed in afirst stage rotor disk 56 a and a connecting member 38 on the compressorside. FIG. 10(c) shows an example in which annular members 112 a and 112b having a different diameter are formed respectively in a first stagerotor disk 57 a and a connecting member 39 on the compressor side, andthe ends thereof are made to abut on each other, to prevent the steamleakage from the bolt hole 25.

[0058] In the sealing structure according to this modified example, inaddition to the action and effect exhibited by the sealing structureaccording to the second embodiment, the first stage rotor disk 55 a andthe annular member 110 a and the like are integrally formed, and hence adeviation of the annular member 110 a and the like do not occur.Therefore, it is not necessary to provide deviation preventing means forthe annular member 110 a and the like, and hence the structure becomessimple, and the reliability can be increased. Further, since it has anintegral structure, the strength can be also increased, to therebyimprove the durability. The sealing member explained in the firstembodiment and the like may be provided on the sealing plane where theannular member 110 a or the like comes in contact with the connectingmember 37 on the compressor side or the like. By having such astructure, the steam sealing performance can be further increased, andthe steam leakage can be reduced by this, and hence the thermalefficiency of the gas turbine can be improved.

[0059] Third Embodiment

[0060]FIG. 11 is a local sectional view that shows a sealing structureof a spindle bolt according to a third embodiment of the presentinvention. This sealing structure has a feature in that the bolt holeprovided in the first stage rotor disk is adhered to the spindle bolt,to thereby seal the steam leaking from the through hole. As shown inFIG. 11(a), a bolt hole 26 for passing a spindle bolt 21 therethrough isprovided in a first stage rotor disk 58 a, and a taper 26 a is formed atthe opening of the bolt hole 26. The spindle bolt 21 comprises a largediameter portion 21 a and a small diameter portion 21 b, and a taper 21c similar to the taper 26 a is formed between the large diameter portion21 a and the small diameter portion 21 b. A bolt hole 70 larger than thelarge diameter portion 21 a is formed in a connecting member 40 on thecompressor side, so that the large diameter portion 21 a of the spindlebolt 21 can pass therethrough.

[0061] The spindle bolt 21 is inserted into the bolt hole 26 provided inthe first stage rotor disk 58 a, so that the taper 21 c of the spindlebolt 21 comes in contact with the taper 26 a of the bolt hole 26. Thoughit is not clear from FIG. 11, the spindle bolt 21 passes through from asecond stage rotor disk to a third stage rotor disk. The first stage tothe third stage rotor disks are fixed by fastening a nut from outside ofthe third stage rotor disk. The taper 21 c of the spindle bolt 21 isallowed to adhere more firmly to the taper 26 a of the bolt hole 26provided in the first stage rotor disk 58 a, by fastening the nut.

[0062] The steam on the first stage rotor disk 58 a side tends to leaktowards the compressor side through a gap between the bolt hole 26 andthe spindle bolt 21. In this sealing structure, however, since the taper26 a of the bolt hole 26 and the taper 21 c of the spindle bolt 21adhere to each other, the leakage of the steam in this part can beprevented. If a sealing member is provided between the spindle bolt 21and the bolt hole 26, the sealability can be further increased, which ispreferable. Alternatively, as shown in FIG. 11(b), a step 59 ax may beprovided in a first stage rotor disk 59 a, so as to abut on a stepprovided in a spindle bolt 22, to thereby seal the steam, without usingthe taper. Further, as shown in FIG. 11(c), a sealing member 90 may bearranged between the spindle bolt 21 and the bolt hole 26, so that theinternal surface of the bolt hole 26 and the outer circumference of thespindle bolt 21 come in line contact with this sealing member, tothereby seal the steam. According to such a line contact, the steamsealing performance can be increased than by a surface contact, andmachining becomes easy, which is preferable. In this sealing structure,since neither a tubular member nor an annular member as in the abovesealing structures is required, steam leakage can be prevented with asmall number of parts. Further, since the tubular member or the like isnot used, the rotation balance is hardly lost, and a trip of the gasturbine due to the spindle vibration hardly occurs, thereby enablingstable operation.

MODIFIED EXAMPLE

[0063]FIG. 12 is a local sectional view that shows a sealing structureof a spindle bolt according to a modified example of the thirdembodiment. This sealing structure has a feature in that in the sealingstructure, an internal thread is provided at an opening 27 a of a bolthole 27 provided in a first stage rotor disk 60 a, an external threadengaging with the internal thread is provided on a spindle bolt 23, andthe both screws are fastened at the opening 27 a of the bolt hole 27 toseal the steam.

[0064] The steam on the first stage rotor disk 60 a side leaks through agap between the bolt hole 27 and the spindle bolt 23. In this sealingstructure, however, since the spindle bolt 23 and the bolt hole 27 arefastened by the screw, the steam is sealed in this part. Particularly inthis sealing structure, since the steam is sealed by the screw, thesealing performance becomes considerably high, as compared with thesealing means such as the surface contact or the line contact describedabove. Therefore, steam leakage can be prevented substantiallycompletely, and hence the steam can be used for cooling the rotor bladewithout being wasted. Further, in the sealing structure, the adhesionbetween the spindle bolt 21 and the like and the bolt hole 26 and thelike becomes weak due to the thermal expansion of the spindle bolt (seeFIG. 11), and as a result, the steam leakage may occur. In this sealingstructure, however, since the spindle bolt 23 and the bolt hole 27 arefastened by the screw, the sealing performance can be stably exhibited,regardless of the expansion of the spindle bolt 23.

[0065] Fourth Embodiment

[0066]FIG. 13 is a local sectional view that shows a sealing structureof a spindle bolt according to a fourth embodiment of the presentinvention. This sealing structure has a feature in that an elasticmember that can deform in the radial direction of the spindle bolt isprovided between a spindle bolt and a through hole provided in a firststage rotor disk, to thereby prevent steam leakage. On the side of aspindle bolt 29 a according to the fourth embodiment, a sphericalelastic strengthening member 94 is provided. The internal surface of abolt hole 28 provided in a first stage rotor disk 61 a comes in contactwith the spherical elastic strengthening member 94, to thereby seal thesteam. This spherical elastic strengthening member 94 is made of a metalmaterial, since a heat resistance and elasticity are required in thespherical elastic strengthening member 94, and for example, it ismanufactured from a nickel base alloy or the like. The elasticstrengthening member 94 is fitted to a spindle bolt 29 a by welding orthe like. The elastic strengthening member 94 may be provided on thebolt hole 28 side. In this case, as shown in FIG. 13(b), if thestructure is such that a tube 95 fitted with an elastic strengtheningmember 96 is inserted into the bolt hole 28, and a spindle bolt 29 b isinserted into this tube 95, repair and replacement become easy, when theelastic strengthening member 96 is damaged, which is preferable.

[0067]FIG. 13(a) will be referenced next for explanation. When thespindle bolt 29 a is inserted into the bolt hole 28 in the first stagerotor disk 61 a, the side of the elastic strengthening member 94 comesin contact with the internal surface of the bolt hole 28. Since theelastic strengthening member 94 can deform radially, even if the spindlebolt 29 a moves radially, the elastic strengthening member 94 can absorbthe movement and maintain the steam sealing performance. The steamleaking through a gap between the spindle bolt 29 a and the bolt hole 28is sealed by the elastic strengthening member 94, and hence steam hardlyleaks towards the compressor. This sealing structure does not use atubular member or the like as in the sealing structure according to thefirst embodiment and the like, and hence the rotation balance is hardlylost. As a result, the steam leakage can be reduced as much as possible,while keeping a trip of the gas turbine to a minimum.

[0068] As shown in FIG. 13(c), a protrusion 97 may be provided on theside of the spindle bolt 29 c and inside the elastic strengtheningmember 94, to restrict the radial deformation of the elasticstrengthening member 94. It is preferable, because a damage resultingfrom an increase of the deformation of the elastic strengthening member94 can be suppressed by this protrusion. Further, a hard coating may beapplied on the internal surface of the bolt hole 28, so as to protectthe internal surface of the bolt hole 28 from fretting wear due to thecontact with the elastic strengthening member 94. By applying the hardcoating, the wear on the internal surface of the bolt hole 28 hardlyoccurs, thereby the durability increases, and time and energy are notrequired for the maintenance, which is preferable. As the hard coating,a TiC or TiN layer may be physically formed by physical vapor deposition(PVD), other than chromium plating. Further, high-carbon high chromesteel, high manganese steel, a Co—Cr—W alloy (Stellite) or the like maybe welded by a hard facing processing.

[0069]FIG. 14 is a schematic diagram that shows a stem and gas turbinecombined cycle power plant adopting steam cooling for cooling the hotmembers. In this stem and gas turbine combined cycle power plant,thermal energy contained in the exhaust gas of the gas turbine isrecovered by a heat recovery steam generator (HRSG). Steam is generatedby the thermal energy in the recovered exhaust gas of the gas turbine,to drive a steam turbine by the high temperature and high pressuresteam, to thereby generate power by a generator connected thereto. Inthis manner, in the stem and gas turbine combined cycle power plant,since exhaust heat of the gas turbine can be effectively used, thethermal efficiency as the whole plant can be increased.

[0070] Though it is not apparent from FIG. 14, this gas turbine 900 usessteam for cooling hot members, such as rotor and stationary blades androtor disks. Though it is not apparent from FIG. 14, a turbine in whichany one of the sealing structures of the spindle bolt explained in thefirst to the fourth embodiments is used in this gas turbine 900. The gasturbine 900 is connected to a first generator 901, and the gas turbine900 drives the first generator 901 to generate power. The exhaust gas ofthe gas turbine 900 has a temperature of about several hundred degrees,and hence this exhaust gas is guided to the HRSG 902, to generate steam.

[0071] The steam generated in the HRSG 902 is first guided to a highpressure steam turbine 903, to drive this. The exhaust steam of the highpressure steam turbine 903 is guided to the gas turbine 900, and usedfor cooling hot members, such as the rotor blade and the stationaryblade. The steam having cooled the hot members in the gas turbine 900 isguided to a mixing chamber 904 and supplied to an intermediate pressuresteam turbine 905. The steam having driven the intermediate pressuresteam turbine 905 is supplied to a low pressure steam turbine 906 todrive this. The high pressure steam turbine 903, the intermediatepressure steam turbine 905, and the low pressure steam turbine 906 areserially connected, to rotate a second generator 907 connected with theoutput shafts thereof, to thereby generate power.

[0072] The steam having driven the intermediate pressure steam turbine905 and the low pressure steam turbine 906 is recovered to a water formby a steam condenser 908, and then supplied again to the HRSG 902 by apump 909. The water is turned into steam again by an evaporator (notshown) provided in the HRSG 902, superheated by a superheater (notshown), and then supplied to the high pressure steam turbine 903 torepeat the process.

[0073] In this stem and gas turbine combined cycle power plant, the gasturbine 900, to which any one of the sealing structures of the spindlebolt explained in the first to the fourth embodiments is applied, isused. Therefore, since the amount of steam leaking through a gap betweenthe spindle bolt and the bolt hole can be reduced, precious steam can beeffectively used, thereby suppressing a loss to a minimum. As a result,the thermal efficiency of the steam and gas turbine combined cycle powerplant can be improved.

[0074] As explained above, in the sealing structure of the spindle boltof this invention, the circumference of the spindle bolt is covered witha tubular member, so that the steam leaking through the bolt holeprovided in the first stage rotor disk is sealed by this tubular member.Therefore, the steam leakage is reduced, and the steam can beeffectively used, and hence the operation cost can be reduced. Further,the cooling steam is generated from exhaust gas of the gas turbine, andafter having cooled the rotor blade, the steam drives the intermediatepressure steam turbine and the like. The steam leakage in this part canbe reduced, and a decrease in the output of the steam turbine can besuppressed. As a result, the thermal efficiency as the steam and gasturbine combined cycle power plant is improved.

[0075] In the sealing structure of the spindle bolt of the presentinvention, two annular members having a different diameter are providedbetween the first stage rotor disk and the connecting member on thecompressor side, and a spindle bolt is made to penetrate between thesetwo annular members, to thereby prevent the steam leaking from the bolthole, through which the spindle bolt passes. Therefore, since the steamleakage is reduced to effectively use the steam, the operation cost canbe reduced by this. Further, since the consumption of the steam in thispart can be reduced, the thermal efficiency as the steam and gas turbinecombined cycle power plant is improved.

[0076] In the sealing structure of the spindle bolt of the presentinvention, a metal or ceramics sealant is provided at the end of thetubular member or the annular member, to increase the steam sealingperformance. Therefore, since the steam leakage can be further reduced,the steam can be used more effectively, and hence the thermal efficiencyas the steam and gas turbine combined cycle power plant is improved.

[0077] In the sealing structure of the spindle bolt of the presentinvention, a step or the like is provided in the first stage rotor diskor the like, to prevent the tubular member or the annular member frommoving radially outwards of the rotor disk due to the centrifugal force.Since the rotor disk of the gas turbine rotates at a high speed, thestructural members in the rotating system are subjected to a largecentrifugal force. When the tubular member or the annular member iseccentric due to the centrifugal force, the rotation balance is lost andspindle vibration increases, thereby a trip of the gas turbine mayoccur. In this sealing structure, since the movement of the tubularmember or the like is hindered by making the step or the like abut onthe tubular member, a deviation of the tubular member or the like can besuppressed. As a result, since the gas turbine can be operated withoutlosing the rotation balance, a trip of the gas turbine can besuppressed.

[0078] In the gas turbine according to the present invention, thecircumference of the spindle bolt is covered with a tubular member, andthe steam leaking through the bolt hole provided in the first stagerotor disk is sealed by this tubular member. Thereby, the steam leakagein the spindle bolt can be reduced, and hence in this gas turbine,wastefulness of the cooling steam can be suppressed. Further, in a steamand gas turbine combined cycle power plant using this gas turbine, thethermal efficiency can be increased.

[0079] In the gas turbine according to the present invention, twoannular members having a different outer dimension are arranged betweenthe first stage rotor disk and the connecting member on the compressorside, and the spindle bolt is passed between these two annular members,to prevent the steam leaking from a bolt hole, through which the spindlebolt passes. Therefore, steam leakage in the spindle bolt can be reducedto suppress wastefulness of the cooling steam. Further, in a steam andgas turbine combined cycle power plant using this gas turbine, thethermal efficiency can be increased.

INDUSTRIAL APPLICABILITY

[0080] As described above, the sealing structure of the spindle bolt andthe gas turbine according to the present invention are useful for a gasturbine that uses steam as a cooling medium for hot members such as arotor blade and a rotor disk, and are suitable for increasing theefficiency, by reducing leakage of the steam and increasing the useefficiency of the steam.

1. A sealing structure of a spindle bolt, wherein rotor disks and a connecting member on a compressor side are fixed by a spindle bolt, and between a first stage rotor disk and the connecting member on the compressor side, of a turbine rotor in a gas turbine having a steam path therein, the circumference of the spindle bolt is covered with a tubular member in which a section thereof vertical to the axial direction includes a section of a bolt hole for passing the spindle bolt therethrough, and the ends of the tubular member are made to abut on the first stage rotor disk and the connecting member on the compressor side, respectively.
 2. A sealing structure of a spindle bolt, wherein rotor disks and a connecting member on a compressor side are fixed by a spindle bolt, and of a turbine rotor in a gas turbine having a steam path therein, a first annular member and a second annular member arranged inside the first annular member are arranged so that the ends thereof abut on the first stage rotor disks and the connecting member on the compressor side, and the spindle bolt is passed between the first annular member and the second annular member.
 3. The sealing structure of a spindle bolt according to claim 1 or 2, wherein a sealant is provided at least on one side of between the end of the tubular member or the annular member and the first stage rotor disk, and between the end of the tubular member or the annular member and the connecting member on the compressor side.
 4. The sealing structure of a spindle bolt according to claim 1 or 2, wherein a protrusion or a step that hinders the tubular member or the annular member from moving radially outwards of the rotor disk, is provided at least on one side of the first stage rotor disk and the connecting member on the compressor side.
 5. A gas turbine that has a plurality of rotor disks having a rotor blade on the periphery thereof, which cools the rotor blade or the rotor disk, and other hot members by steam, the gas turbine comprising: a compressor that compresses air to produce combustion air; a combustor that supplies fuel to the combustion air produced by the compressor to generate combustion gas; and a turbine rotor having a feed path or a recovery path for the steam therein, in which rotor disks and a connecting member located on the compressor side are fixed by a spindle bolt, wherein between the first stage rotor disk and the connecting member, the circumference of the spindle bolt is covered with a tubular member in which a section thereof vertical to the axial direction includes a section of a bolt hole for passing the spindle bolt therethrough, and the opposite ends of the tubular member are made to abut on the first stage rotor disk and the connecting member on the compressor side, respectively.
 6. A gas turbine that has a plurality of rotor disks having a rotor blade on the periphery thereof, which cools the rotor blade or the rotor disk, and other hot members by steam, comprising: a compressor that compresses air to produce combustion air; a combustor that supplies fuel to the combustion air produced by the compressor to generate combustion gas; and a turbine rotor having a feed path or a recovery path for the steam therein, in which rotor disks and a connecting member located on the compressor side are fixed by a spindle bolt, wherein a first annular member and a second annular member arranged inside the first annular member are arranged so that the ends thereof abut on the first stage rotor disks and the connecting member, and the spindle bolt is passed between the first annular member and the second annular member. 